Animal protein resin-plastic compositions and manufactures incorporating animal skins and/or leather and/or gelatin powder therein, the powder therein, and method of producing the same

ABSTRACT

The present invention relates to methods, compositions, and articles manufactured from scrap treated skin and/or leather which has been finely pulverized and mixed with synthetic resin. It further includes a method for the manufacture of improved leather products made from animal skin and/or leather and/or animal gelatin including the products derived therefrom and the method of producing skin and/or leather powder by use of steam and pulverization for combining with a fluid plastic material or resin in which the powder is uniformally dispersed in the plastic resin material for molding, extruding or manufacture of sheet material or for incorporation into coatings, paint or other plastic resinous products.

This is a division of application Ser. No. 07/515,318 filed Apr. 23,1990, which is a continuation of Ser. No. 07/221,904, filed July 20,1988, now abandoned, which is a divisional of Ser. No. 07/068,347, filedJuly 1, 1987, now U.S. Pat. No. 4,834,762.

The present invention pertains to improved leather products made fromanimal skin and/or leather and animal gelatin and methods ofmanufacturing the same. It also pertains to the method of reducinganimal skin and/or leather to a fine powder compatible with resin andplastic compounds.

All vertebrates, including humans have skin containing collagen, afibrous protein. Collagen protein is very complex structure, andinsoluble in water. This invention also pertains to the method ofpulverizing the collagen fibers to a fine powder form and compoundingthe powder with plastic to form a product superior to natural leather.

Prior art artificial leather had many shortcomings as compared tonatural leather. This invention provides a manmade leather includingmaterial having the desirable qualities of natural leather such a feel,suppleness, texture, resistance to static electricity, and absorption.It is superior to natural leather because it does not have thedisadvantages such as the need for constant care or susceptibility tomold, fading, and dirt. This reconstituted leather looks and feelsbetter the longer it is used. Unlike the natural leather, it does notage as quickly.

BACKGROUND OF THE INVENTION

In the past, scrap skin and leather have been discarded as having nouseful purpose. The pieces of scrap were insufficient to utilize forleather goods of the like. People had attempted to grind and pulverizethe skin/leather and mix it with resins so that commercial articlescould be made therewith. Skin and leather breathes and because of thisit has a comfortable feeling when worn as a garment or as footwear.Synthetics generally do not breath. The prior art incorporatingskin/leather into the resin was unsatisfactory because the particles ofskin/leather tended to clump or lump together. The failure of theparticles to be uniform in distribution throughout the synthetic resinmaterial created undesirable characteristics to the material moldedtherefrom.

Natural leathers have long been used for clothing and other articles.They wear well and are supple and tough as well as attractive inappearance. Unfortunately, natural skins and leathers are limited insupply and because of troublesome tanning processes, become quiteexpensive when used in a manufacture of articles of clothing,accessories or the like. Because of different shapes and sizes of theoriginal animals, a special skill is needed to cut and make them intoclothes, etc. and scrap material and waste is common.

Previous attempts have been made to pulverize the skin/leather into apowder. When used with a resin, the powder tends to cake.

Recently, various artificial and synthetic leathers have been developedas a substitute for natural leather. One typical example is a syntheticleather comprising a substrate of woven or knitted fabric and asponge-like surface made of formed compositions such as vinyl chloride,polyamides or polyurethanes treated with the denatured polyamides,polyurethanes, or polyacrylic acid derivatives.

Another example is an artificial leather having a porous structurecomprising a three-diminsionally entangled fiber member made of specialfibers such as hollow, lotus-root-like fiber, a bundle of very finefibers, and a binder mainly of an elastomer(polyurethane) and the like.

These synthetic or artificial leathers have characteristics very similarto those of natural leathers and have excellent insulating qualities andyet have excellent air and moisture permeability and water repellency.However, water absorption in these artificial and synthetic leathersoccurs only through capillary action, and water absorption due toswelling of tissues does not occur in them. While air permeability iscontrolled in natural leathers as the porosity in the tissues isadjusted when the tissues swell, synthetic or artificial leathers do nothave such an action.

Natural skins refer to untanned pelts. Natural leathers refer to leathertanned pelts. Tanned pelts require tanning treatment with tanning orchrome. Numerous attempts have been made to pulverize naturalskin/leather into a powder and to mix it with synthetic resins to bemolded into sheet using the resin as a binder. If natural skin orleather could be molded together with synthetic resin, in a propermanner, a number of advantages would be apparent. For one, the presenceof natural skin or leather in the molded product would improve water andmoisture absorption due to swelling and provide a molded product havingan excellent feel without stickness. Secondly, the presence of skin orleather powder in the molded product should provide suppleness andresillient toughness to the product not obtained in other resin moldedproducts.

Thirdly, the presence of skin and leather powder should reduce staticbuild-up and eliminate the static discharges and the discomfort causedthereby. It would also reduces the adherence of dust caused by staticbuild-up.

Further, the heat insulating property of the resin molded productscontaining skin and leather powder should be greatly improved.

Difficulties have been experienced in pulverization, since longer fiberssometimes became entangled depending on the type of skin or leather(whether pelt of a pig or cow; a particular portion of a pelt, etc. orother properties such as whether the pelt is of a young animal or of anadult; or the type of tanning or storage conditions under which thepelts were treated).

Furthermore, problems have been encountered in going from a pilot plantto actual production.

Other problems have been noted and it was also found that due to forceddrying and impact shearing, grains of the skin or leather powder gotentangled and took on an appearance of unraveled cotton during storage.This powder eventually flocculated making it difficult to mix withsynthetic resin.

Flocculated skin or leather powder will not ordinarily mix evenly in thesynthetic resin due to the lack of lubricity. This making it impossibleto give the product properties specific to leather and interferes withthe good characteristics of the molded resin itself.

The presence of flocculated skin or leather powder further led todefectively high increases in resistance in the mixing cylinders, dietools used for extrusion or injection molding. Thus wear of the cylinderinner wall or damage to the dies or molding tools developed. Whenresistance in extrusion or injection was high, it was necessary to uselarger molding machines and the molded products had deformations due toshrinkage, etc.

Although the problem of fluidity in molding with a calender roll mighthave been minimal, flocculated skin or leather contained in thesynthetic resin would of then agglomerate or cake, and the product wouldbecome uneven on the surface. The caked skin/leather powder would alsocause cuts or abrasions in the surface of the resin material.

Further in the past, when mixed with a paint, the flocculated skin orleather powder became unevenly distributed in the coating layer causingbumps or scars in the coated surface. Additionally, the paint, when usedin a spray gun, tended to clog the nozzle of the gun.

Other problems in the prior developments occurred when a film of lessthan 0.1 mm thickness was to be produced. The powder caused bumps in thefilm and weakened certain areas which eventually led to tearing of thefilm.

Further, in the prior art method, problems of uneven grain sizedistribution and longer fibers were encountered in pulverizing cow hidesbecause of their tough collagen fiber. With pig skin, on the other hand,oil/fat content in the skin hampered the efficiency of pulverization.

OBJECTS AND SUMMARY OF THE INVENTION

An object of this invention is to provide a skin/leather powder whichdoes not agglomerate or flocculate, but maintains a granular stateduring the process of its manufacture, storage or when mixed withsynthetic resin.

Another object of this invention is to provide a molded product using amixture of synthetic resin and uniformly distributed skin/leather powderso that the product will have combined characteristics of both leatherand molded resin.

Still another object of the present invention is to provide askin/leather powder which can be uniformly distributed in a liquid suchas paint, so that the coated layer of the paint will be uniformlydistributed with the powder.

A further object of this invention is to provide a skin/leather powderwhich effectively mixes with synthetic resin solutions, emulsions ormolten (including liquid polymers) resins to be used as a coating ormaterial for making transfer films for lamination.

Yet a further object of this invention is to pulverize the powder andmake it "granular" rather than "fibrous". The granules do not becomeentangled permitting the producing of finer powders which will notflocculate and which will have a specific gravity of about 0.38-0.5.Granular powder does not require special separation techniques andlonger grains can be used and mixed well with resin because of theirhigh lubricity permitting uniform distribution in the molded product.This permits "loading" (increasing the amount of powder ordinarily used)without seriously affecting the resultant product.

Another object of this invention to produce a product having anexcellent insulating factor which is soft to the touch and is notsticky.

Still a further object of this invention is to provide a leather/plasticproduct which is supple, tough and durable as well as having a naturallustrous leather appearance.

Still a further object of this is to provide a method which allows forthe utilization of waste material such as scraps of various leathers invarious shapes and sizes heretofore discarded.

A further object of this invention is to provide a leather powder whichcan be easily added to a plastic resin composition.

Yet another object of this invention is to provide a leather compositionhaving characteristics similar to natural leather and having excellentair and water permeability and moisture absorption.

Yet a further object of this invention is to provide a leathercomposition in which the porosity of the material adjusts in the mannerof natural leather to permit the material to breath even when absorbingmoisture.

Yet another object of this invention is to provide a resin and leatherpowder mixture which can be molded, extruded, or otherwise formed intosheet material which is lustrous and has an excellent feel.

Still further object of this invention is to provide a leathercomposition which prevents static build-up and adherence of dust theretoas well as elimination or reduction of static discharge.

Yet a further object of this invention is to provide a leathercomposition which has high insulating properties.

Still a further object of this invention is to provide a method forpulverizing simultaneously various different types of skins, pelts orhides whether of young animal or adult or of different types of animals.

Another object of this invention is to provide a method for producing apowder form leather which avoids entanglement of the fibers orunraveling during storage making it difficult to mix with syntheticresin.

Still another object of this invention is to provide a method forproducing a powder which will reduce wear and tear on machinery dies andother tools used in the production thereof.

Another object of this invention is to provide a leather compositionwhich has sufficient fluidity to prevent problems during calendering orproduction operations.

Yet another object of this invention is to provide a composition whichwill mix with paints readily without causing lumps or agglomation thusgiving a smooth flowing paint, and thus avoiding surface defects in thepaint when applied, and to provide a paint in which the films or coatingwill stand up under harsh conditions without cracking, crazing or thelike.

The growing importance of computers and other sophisticated machinery intoday's complex world is axiomatic. Plastic is an indispensable part ofthis equipment. Higher quality plastics facilitate the production ofeven more advanced equipment. Thus, another object of this invention isto provide a new compound of collagen gelatin and plastic which isabsorbent, supple, attractive to the eyes and similar to naturalleather, and which has the same texture and feel as natural leather withpliancy in temperatures as low as -40° C. with a feeling of warmth incold weather and coolness in hot weather.

Still another object of this invention is to provide a gelatin-plasticmaterial which is not sticky to the touch and which is air permeable sothat it is resistant to water and wear and does not mold or fade.

Still another object of this invention is to provide a gelatin-plasticcompound which can be cleaned and dyed easily and treated like naturalleather with shoe polish, leather cleaner, or the like.

Yet another object of this invention is to provide a collagen gelatinand plastic composition which is electroconductive and resistant tostatic electricity and does not readily attract dust.

A further object of this invention is to provide a gelatin plasticmaterial which can be processed with leather working equipment intosuede, embossed leather, shrunken leather, corrected grain leather,enameled leather, or mat leather. For embossing, it can take on thetexture of crocodile, ostrich, elk leather etc.

Still a further object of this invention is to provide a gelatin plasticwhich is more absorbent and more durable and oil-resistant than ordinaryplastic.

Another object of this invention is to provide a gelatin plasticcomposition having greater adhesive properties than oridinary plasticwhen in the fluid state.

Yet another object of this invention is to provide a gelatin plasticmaterial for use on tool surfaces and which is more stable on wet orfrozen roads than synthetic rubber and has excellent vibration and shockresistance. This makes it also useful in automobile frames.

Another object of this invention is to provide a gelatin plasticcomposition which is easier to shape, inject or extrude than ordinaryplastic and retains its resilient stable qualities even undertemperatures as low as -40° C.

In summary, this invention relates to the production of a leather powderwhich can be used in furniture or furnishings, paint, or moldedmaterials or the in the production of leather type products for use inthe automotive, boating, or aircraft industries or the like.

These and other objects of this invention will be apparent from thefollowing description and claims.

In the accompanying drawings which illustrates by way of example variousembodiments of this inventions;

FIG. 1, is a schematic view of an apparatus for heating skin/leatherwith steam.

FIGS. 2 and 3, are schematic views of an apparatus for classifying thepulverized skin/leather according to the grain sizes.

FIGS. 4, 5 and 6, are electron-microscopic enlargements magnified 100times of pulverized skin/leather according to prior art methods.

Photographs 7 and 8, are photographic views showing the front and backof a calender-rolled sheet using skin/leather powder pulverized by aprior art method.

FIG. 9, is photographic electron-microscopic view magnified 101 timesshowing the skin/leather powder according to the present invention.

FIG. 10, is a photographic electron-microscopic view of the skin/leatherpowder magnified 100 times of a modification of the invention.

FIG. 11, is a graph showing the grain distribution of the skin/leatherpowder according to the modified invention. In this figure, the ordinaterepresents the amount of distribution in weight percent and the abscissathe grain size in microns. Numerical values given the graph representthe amount of distribution by weight percent.

FIG. 12, is a reference list to show the correspondence between meshsize and micron size.

FIGURES 1 THROUGH 3

In order to obtain a fine powder having a specific gravity of about 0.38to about 0.5, which will not cake or agglomerate when mixed with asynthetic resin, it has been found necessary to treat the skin and/orleather tanned with chrome or tannin with steam.

First the skin and/or leather is shredded into strips or chips. Stripsinitially of 30 mm lengh were utilized; however, as shaven scraps arelong and twisted, it was more desirable that they be cut to a size ofabout 5 mm prior to steam treatment.

The steam treatment is continued until the specific gravity of theskin/leather powder to be produced reaches 0.38-0.50. Duration of thesteam treatment varies depending on the nature and amount of theskin/leather to be treated and the pressure and temperature of thetreatment chamber.

Chips or strips after cutting are charged into the closed treatingchamber 1 as shown schematically in FIG. 1. The treating chember 1includes an agitator diagrammatically shown at 2. A steam jacket 3encloses the chamber 1. Steam A is fed into steam line 4 and exhaustsfrom steam line 5. A valve 6 controls the pressure in the chamber 1 toabout 1 kg/cm². The chamber is maintained at between 100° C.-119° C. andthe charge is agitated for about 30 minutes.

The steam treatment is designed to increase the water content of thecharge by about 5-10 wt. percent depending on the type skin and/orleather in the charge. The steam jacket 3 is provided with a steamin-feed line 7 and exhausts at B' through line 8 having a control valve9. Thus steam A as well as steam B can be applied to the chamber 1 withexhaust of steam A' and B' respectively from both the chamber 1 and thejacket 3.

The jacket 3 is used to simultaneously effect heating from the outsideas well as from the inside of the chamber 1. Adjustment is made toobtain a water content in the skin and/or leather to about 15 wt.percent or less (primary drying).

A secondary drying is necessary to reduce the water content to about 5wt. percent or less and ideally approximately 3 wt. percent or less. Theresultant charge is subsequently pulverized into a powder.

The use of split or shaven leather which has been tanned with chrome ortannin prevents fungus and deterioration of the powder duringprocessing. Heating time in the chamber is determined by the temperatureof the steam, pressure, type of chips or strips in the charge etc. Thesteaming is maintained for a sufficient time at a temperature rangingfrom between 100° C. and 119° C. to permit swelling and unraveling bythe steam of the collagen fibers in the chips or strips. The fibers tendto shrink upon heating thus permitting the unraveling and loosening ofthe fibers preparatory to pulverization. The higher the temperature andpressure, the shorter the heating to achieve the desired swellingeffect. Temperatures and pressures too low, make the process unsuitablefor production. It should be noted that chrome or tannin tanned skinand/or leather having been steam-heated for swelling, tend to evaporateso that the collagen fibers shrink and loosen and become somewhatdisentangled with each other.

Skin and/or leather not tanned becomes hardened after drying making itimpossible to pulverize the same. It was found, that where the skinand/or leather had not swollen fully, the resultant powder showedflocculation and had an apparent specific gravity 0.2-0.3 which wasbelow the required about 0.38-0.5.

It was also found that if the water content of the skin and/or leathermaterial is extremely low (20-30 wt. %), the resultant powder obtainedalso flocculated and had a specific gravity too low of 0.2-0.3. Thus, aspecific gravity of 0.3 or lower is impractical for actual use. Further,if the skin and/or leather is heated in boiling water and in essencecooked, it will harden and be unsuitable for use despite subsequenttreatments.

EXAMPLE 1A AND 1B

Pulverization is carried on in a pulvering mill such as a Fine VictoryMill (not shown).

(Example 1A) The Fine Victory Mill is operated at 7000 rpm,no-load/loaded operation at 17.2/20 (ampere) with a slot half opened. Inanother example or operation, the rotation was 7800 rpm, no-load/loadedoperation at 15.8/20 (ampere) and with the slot fully opened (Example1B).

The skin/leather powder thus obtained was sifted using a 40 mesh sieveand the grain size distribution was studied.

EXAMPLE 1A

    ______________________________________                                        Under Sieve Above Sieve                                                                              Distribution Amount                                    ______________________________________                                         40          60 mesh   2.8%                                                    60          80 mesh   9.7%                                                    80         100 mesh   9.7%                                                   100         150 mesh   25.7%                                                  150         200 mesh   13.9%                                                  200         300 mesh   33.7%                                                  300 mesh               4.5%                                                   ______________________________________                                         ("40 mesh" of "Under Sieve" means the skin/leather powders which passed 4     mesh sieve and "60 mesh" of "Above Sieve" means the skin/leather powders      which did not pass 60 mesh sieve.)                                       

Skin/leather powder was obtained by a similar treatment except that acoloring process was included in the steam-heating has the followinggrain distribution:

EXAMPLE 1B

    ______________________________________                                        Under Sieve Above Sieve                                                                              Distribution Amount                                    ______________________________________                                         40          60 mesh   5.7%                                                    60          80 mesh   7.0%                                                    80         100 mesh   5.7%                                                   100         150 mesh   39.4%                                                  150         200 mesh   30.0%                                                  200         300 mesh   12.2%                                                  300 mesh               0%                                                     ______________________________________                                    

Skin/leather powder having the above grain distributions are suitablefor use in mixture with various resin materials for molding. Any type ofmolding methods such as calender roll, extrusion or injection can beused.

The skin/leather powder was measured to have a specific gravity ofbetween about 0.38-0.50.

The specific gravity as used in the present specification is an aeratedbulk density. Powder is charged into a vessel of 100 cc capacity througha sieve by shaking the same, leveling off at the top and then weighing.The values are expressed by dividing the powder weight with 100.

The relation of mesh size micron in the grain size in this specificationis shown in the attached list (FIG. 12).

EXAMPLE 2

Using an air classifier, the skin/leather powder was classified intodifferent classes for use in thin films or layers such as paint, coatingor laminated film according to the true specific gravity.

This classification will be described in conjunction with FIGS. 2 and 3.The reference number 11 denotes a feeder which introduces saidskin/leather powder and continuously feed the same into an airclassifier 12 (Micron Separator). The air classifier 12 has a rotor 12awhich suctions and classifies the skin/leather powder supplied via aninlet port 12b according to the true specific gravity. A trubo-fan 13feeds the powder into a back filter tank 14 for classification. Coarsepowder is classified and taken out from a rotary valve 12c and finepowder from a rotary valve 14a. The reference number 12d denotes asecondary air inlet port, and 12e an outlet port for classified finepowder.

Using the classifier of the above construction, 5 kg of skin/leatherpowder was treated with the rotation of the rotor 12a at 600 rpm,secondary air supply of 4.0 m³ /min and air for dust collection of 12 m³/min and 2.05 kg of fine powder was obtained.

As in seen in the graph (FIG. 11) showing the grain size distribution,the fine powder thus classified had a mean grain diameter of 24.5microns, with the majority having that of less than 50 microns. Theapparent specific gravity of the fine powder was 0.38-0.50.

With the fine powder thus obtained, the powder grains do not becomeentangled and each discrete grain is present without flocculation orcaking.

FIGS. 4 THROUGH 10

FIGS. 4 through 6, are microphotographs of test samples of powderproduced from pulverization of the skin and/or leather which has beentanned chrome and shredded into strips about 30 mm length. The resultantmaterial was dried to a water content of about 5 wt. percent (on a wetbases) (or 1.9-5.0 percent in the actual pilot plant) and charged into ahammer-type pulverizing mill under the following conditions:

EXAMPLE 3

    ______________________________________                                        Rotation              3800 rpm                                                Sieve screen           32 mesh                                                Charged material        0.2 kg                                                Treatment time         27 sec                                                 Amount of product       0.2 kg                                                ______________________________________                                    

Upon pulverization under the foregoing conditions, the powder ofskin/leather having the following grain size distribution was obtained(as measured in shorter diameter when the grain is fibrous).

    ______________________________________                                        Under Sieve  Above Sieve Distribution Amount                                  ______________________________________                                                     32 mesh     0.8%                                                  32          48 mesh     2.4%                                                  48          60 mesh     8.2%                                                  60          100 mesh    15.5%                                                100          150 mesh    18.4%                                                150 mesh or smaller      54.75%                                               ______________________________________                                    

The charge was not treated with steam.

The resultant specific gravity of the product thus obtained was very lowat 0.1 to 0.2. The images in FIGS. 4 through 6 are enlarged by 1.6 timesat the of printing. Although grains finer than 150 mesh (ca. 100microns) were predominant in the powder, longer fibers (ca. 800 microns)were also present, lowering the apparent specific gravity.

The test results were defective in that the longer fibers becameentangled and unraveled depending on the types skin and/or leather usedwhether from pig or cow, young animal or adult, etc. The tendency becamemore pronounce in the transition from the pilot plant to actualproduction. During storage, the grains of powder became entangled andappeared as of unraveled cotton. When mixed with synthetic resin, thepowder flocculated and became difficult to mix.

FIGS. 7 AND 8

FIGS. 7 and 8, show a molded product of mixture of synthetic resin andthe skin and/or leather powder produced in the manner above. FIG. 7shows the front and FIG. 8 the back of a sheet molded by a calender rolland a magnification of ca. 2.6 times. Note the flocculated materialshows irregularities on the surface of the sheet. This indicates thatthe resin and powder will not mix evenly and give uniform distribution.Under extrusion, such flocculation causes wear on the equipment. If thematerial is used in a paint, the flocculated powder tends to clog thenozzle of the spray gun.

FIGS. 9 AND 10

FIGS. 9 and 10, show microphotographs of the skin and/or leather powdermade according to the invention.

FIG. 9, shows no fibers present and discrete grains disbursed in thepowder to maintain "a granular state". This photograph shows that thespecific gravity of the invention is substantially greater than thatshown in the powders of FIGS. 4, 5 and 6. Using the classifier(12), 5 kgof skin/leather was treated with the rotor 12a at 600 rpm, secondary airsupply of 4.0 m³ /min and air dust collection of 12 m³ /min, and 2.05 kgof fine powder was obtained. The fine powder classified has a mean graindiameter of 24.5 microns, with a majority have less than 50 microns.Thus the specific gravity of fine powder becomes greater and fallswithin the 0.38-0.50. As compared with FIG. 9, FIG. 10 shows moreuniformity and a higher specific gravity. Note also the fine grain sizeswith no fibers or entanglement.

It has been determined from the various test conducted, that theapparent specific gravity is greater than 0.38 with no entangled orciliary fibers.

The powder considered in FIG. 9, was filtered using a 40 mesh sieve andhad an apparent specific gravity of 0.38-0.50.

When this powder is mixed with various synthetic resins such as vinylchloride depending on the purpose, it was found to become evenly mixedand distributed in the molded resin. Neither flocculation nor cakingoccured in the powder and each discrete grain is dispersed in the moldedproduct. Extrusion and injection molding of the powder resin is similarto that of conventional resins thus preventing wear of apparatus. Thepowder of FIG. 10 contains more than 70 wt. % of grain smaller than 40microns (as measured in smaller or shorter diameter if the grain iselongated). Although this powder is extremely fine and has a grain sizeof 40 microns or less, the powder did not flocculate in any of theprocessing, storage or molding steps with resin. Further, when mixedwith paint, and particularly with resinous coating solutions, the powdermixes well without flocculating and its grains are evenly disbursed.This enables coating of the paint in a thin layer with the powdercontained therein. The grains of the powder being very fine, do notaffect the coated layer surface which becomes even and smooth.

With this development, it is also possible to produce an extremely thinresin film (0.1-0.01 mm), especially a laminated film, without causingunevenness of texture, deformation or warping on the surface. In theexample where 70 wt. % of grains is smaller than 40 microns, themajority of the grain is approximately 100 microns or less and moreparticularly below 40 microns. The powder may be used to form a film ona release paper and then laminated on cloth, paper, resin film, leather,etc.

The attached graph (FIG. 11) shows the grain size distribution in weightpercent measured by classifying the powder with a classifier andsuspending the same in methyl alcohol to measure the grain size using acoal tar counter.

It is apparent from the graph (FIG. 11) that the powder contains 78.7wt. % of fine powder with the grain size of 40 microns or smaller. Asmentioned above, a powder having grain sizes slightly greater than thiscan also be used in mixing with said paint or coating material.Experiments conducted by the present applicant revealed that a goodresult can be obtained if more than 70 wt. % of powder is of a grainsize smaller than 40 microns and if grains exceeding 150 microns areeffectively cut into smaller sizes.

The leather powder mentioned above may become discolored if its fatcontent is high. Therefore, the powder is given fat removing treatment.

The fat removal treatment uses a solvent such as benzine, methylchloride, methyl acetone, and ethyl acetate which elutes oils fromleather. Another treatment washes the leather with hot water and elutesthe fat content from the swollen leather. When using a solvent, theleather should preferably contain less amount of water. Therefore, theleather is ideally subjected to this elution treatment with the solventeither in the stage prior to steam heating, in the stage of drying aftersteam heating, or after the stage of pulverization after drying.

The skin/leather powder thus obtained can be dyed if desired. Suitabledyestuff and method for dyeing must be selected depending on theproperties of the powder. For instance, if the powder is obtained from askin/leather tanned with chrome, then acidic dyestuff such as mono-azo,anthraquinone and carbonium dyes which achieve uniform dyeing andosmotic action (permeation) were used. For a skin/leather treated withtannin, basic dyestuff such as azo, azine and thiazine were used. Acidicmordant dye, direct dye and reactive dye were also added depending onthe use, properties of the powder, etc., and dyeing was conducted undermoisture and agitation. After dyeing, the powder was dried.

The dyeing can be conducted concurrently with steam-heating, oralternately, it can be conducted as a separate step under moisture afterpulverization has been completed. Optimum methods can be employed tosuit the conditions of each plant.

APPLICATION OF POWDER ACCORDING TO THE FIRST INVENTION

Using the powder classified by a 40 mesh sieve and mixed with syntheticresins such as vinyl chloride, various moldings were obtained.

Synthetic resins that can be used in mixture with the present inventionpowder include thermoplastics such as vinyl chloride, vinyl acetate,polyamides, ABS and polycarbonate, polyacrylates thermosetting plasticssuch as phenol, epoxy and urea base resins, polyurethane syntheticrubbers such as chloroprene, butadiene, styrene and olefin base rubbers,and other synthetic resins for molding.

As a typical example, soft sheet of vinyl chloride was molded using thefollowing composition:

    ______________________________________                                        vinyl chloride resin                                                                              100     wt. parts                                         plasticizer         90      wt. parts                                         stabilizer          3       wt. parts                                         skin/leather powder 80-200  wt. parts                                         ______________________________________                                    

A natural leather-like soft sheet was obtained.

The following are the criteria for determining the amount ofskin/leather powder to be mixed in resins for molding. (The values areexpressed in weight percent, and "synthetic resin compound" means amixture of resin, plasticizer, stabilizer, etc.)

(1) For molding sheets:

    ______________________________________                                        skin/leather powder      5-55%                                                synthetic resin compound                                                                              45-95%                                                (synthetic resin compound                                                                             30-95%                                                containing 2-15% gelatin)                                                     ______________________________________                                    

(2) For molding bars, plates and masses such as armrests for chairs,wall, furniture, automobile interior frames such as console boxes,handles, grips:

    ______________________________________                                        skin/leather powder                                                                              20-80%                                                     synthetic resin compound                                                                         20-80%                                                     ______________________________________                                    

(3) For molding containing industrial gelatin

    ______________________________________                                        skin/leather powder                                                                               5-70%                                                     synthetic resin compound                                                                         30-95%                                                     (containing 2-15% gelatin)                                                    ______________________________________                                    

(4) For preparing intermediate material for such as pellets:

    ______________________________________                                        skin/leather powder                                                                               5-80%                                                     synthetic resin compound                                                                         20-95%                                                     ______________________________________                                    

Leather-like moldings of high quality were obtained by any of the abovecompositions.

The above compositions are suitable for molding soft, semi-hardmoldings, and provide features adequate for each hardness. Foamedmoldings are used to manufacture films, sheets plates, bars and massesmentioned above, and in foaming the resin compound mixed with theskin/leather powder, continuous or discrete intervals are formed betweenthe powder and the resin.

APPLICATION OF POWDER ACCORDING TO THE EXAMPLE 2

As the powder according to Example 2 is finer in grains, it hasexcellent lubricity and is sufficiently dry and thus mixes well withsynthetic resin compounds.

Particularly, when 5-45 wt. % of the powder according to Example 2 wasmixed with various synthetic resin solutions (solution, emulsion, ormolten synthetic resin containing liquid polymer) and coated over cloth,non-woven cloth, paper, synthetic leather or leather, sheet productshaving a leather-like surface were obtained.

Similarly, when coated on metal products or resin moldings such asfurniture, automobile interior parts and the like (by means of brush,spraying, etc.) for a thickness of between 0.01 and 0.1 mm, a coatedsurface having a leather-like appearance was obtained.

When said synthetic resin solution was a solution of polyurethane(either one-component type or two-component type), the surface coatinglayer or laminated film layer obtained had a better leather-likeappearance.

It was further found that in applying paints containing the powder ofthe Example 2 by spraying and the like method, a smoother coated surfacewas obtained if the paint mixed with the powder was ground prior to use.This grinding further facilitates spraying of the paint.

It was also found that the powder of Example 2 could be applied on thesurface of a resin molding, cloth, non-woven cloth, paper, leather orsynthetic leather with adhesive.

In any of the above applications, the powder according to the presentinvention does not flocculate but disperses uniformly in the resin andcauses no trouble in coating or spraying operations. Unlike the priorart powder of skin leather, the powder according to the presentinvention will not clog the spray gun and can be easily used forspraying paint in the conventional manner.

Coated layer or film layer thus obtained provided a smooth surfacewithout bumps or whitening phenomenon due to flocculation of the powder.

POST TREATMENT FOR MOLDED PRODUCTS

The surface of the molded products thus obtained is sanded or sandblasted to expose the powder content to the surface.

By immersing the product in hot water, portion of said gelatin or powdercontained in the product can be induced to seep out and form fine poreson the surface.

The surface of products may be embossed with special patterns (such as apattern of a crocodile skin).

Dyes, oils and paints for leathers can be used with the powder of thepresent invention in the same manner as in the ordinary leathers.

TARGET PRODUCTS

As is evident from the foregoing, any type of resin moldings can beproduced using the skin/leather powder of the present invention. Thepowder can also be used for spraying, coating and laminating. It istherefore possible to use the powder in molding everything that is usedin daily life.

White this invention has been described as having a preferred design, itis understood that it is capable of further modifications, uses and/oradaptations of the invention following in general the principle of theinvention and including such departures from the present disclosure ascome within known or customary practice in the art to which theinvention pertains, and as may be applied to the central featureshereinbefore set forth, and fall within the scope of the invention ofthe limits of the appended claims.

What is claimed is:
 1. A powder product, comprising:a) a granularnon-flocculating compatible powder having a specific gravity of fromabout 0.38-0.5 and produced from tanned skin, leather, or tanned skinand leather fragments which have been steam heated to retain the naturalstructure of the skin, leather, or skin and leather for a period of timesufficient to permit the fragments to swell and simultaneously cause thenaturally occurring twisted and tangled collagen fibers therein toshrink, and in so doing, cause said twisted and tangled fibers toautomatically loosen and become less twisted and tangled, andsubsequently the steam heated fragments are dried and pulverized.
 2. Thepowder product of claim 1, wherein:a) said fragments are dried to awater content of less than about 5%.
 3. The powder product of claim 1,wherein:a) said pulverized granules are sifted by using a sieve toobtain particle size distribution ranging from about 40-300 mesh.
 4. Thepowder product of claim 1, wherein:a) said fragments are dried duringsteam heating; and b) said granules are sifted by using a sieve toobtain particles size distribution ranging from about 40-300 mesh. 5.The powder product of claim 3, wherein:a) said pulverized granules aresifted such that about 33.7 percent of granules are in the size range ofabout 200-300 mesh.
 6. The powder product of claim 4, wherein:a) saidpulverized granules are sifted such that about 39.4 percent of granulesare in the size range of about 100-150 mesh.
 7. The powder product ofclaim 1, wherein:a) said granules are air classified in an airclassifier to remove dust and sized into at least two classes by size ofgranules with at least one larger granule size class and one smallergranule size class; and
 8. The powder product of claim 7, wherein:a)said granules are air classified to have 70 wt. % of powder of a grainsize less than about 40 microns.
 9. The power product of claim 1,wherein:a) said fragments comprise shredded chips, strips, or chips andstrips of said tanned skin, leather or tanned skin and leather.
 10. Thepowder product of claim 9, wherein:a) said chips, strips, or chips andstrips have a length of about 30 mm. prior to steam heating.
 11. Thepowder product of claim 9, wherein:a) said chips, strips, or chips andstrips have a length of about 5 mm. prior to steam heating.